Yeah, I tend to use the frag grenade strategy for the bosses. Practically three to five seconds of combat and then it finishes. It's kind of funny.
But the intention of the game was how you managed to get through the scene, whether through stealth, combat, hacking or social. It just had a variety of styles. Besides, there were many rewards, though I feel the game leant more towards Stealth, due to the vast experience points you get for being merciful, a ghost, etc.
The hacking did get tedious though, that's true. Towards the end, I simply just kept on nuking the nodes. I agree the ending could have been somewhat better. Oh well, perhaps I'll have to return to Deus Ex. It's somewhere on my shelf. I think.